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Full text of "The manufacture and properties of iron and steel"

160
METALLUKGY OF IRON AND STEEL.
Combustion of carbon (coal) with no excess of air: 1 kg. carbon-f-8.87 cu. metres air=l.S6 cu. m. C02+7.01 cu. m. K.
Combustion with 100 per cent, excess:
1 kg. carbon +17.74 cu. m..air=1.86 cu. m. C02+14.02 cu. m. N
+1.87 cu. m. 0.
The aquations given herewith represent the volume of air required by each kg. of carbon and the volume of the products caused by the combustion under two different conditions. Excess air means a considerable loss of heat, but there will be a loss in the waste gases even if there be rlo excess of air, for the products of combustion carry off a great deal 'of sensible heat. The amount so carried will depend upon the temperature of the waste products, as shown in Table IX-B. If the gases from a coal-fired boiler
TABLE IX-B. Loss of Heat in Products of Combustion of Hard Coal.
	Temperature of gases ; degrees Cent.				
	100° C. 210° F.	200° O. 390° F.	300° C. 570° F.	400° 0. 750° F.	600° C. 1110° F.
Specific heat of waste gases — No excess air ..........................	.328 .327 .324 .322 .320 .318 3.8 4.5 5.1 5.8 6.5 7.2	.336 .334 .331 .328 .326 .324 7.5 8.9 10.3 11.7 13.0 14.4	.344 .341 .338 •335 .332 .329 11.3 13.4 15.4 17.5 19.5 21.6	.352 .348  . .345 .341 .338 .334 15.5 18.4 21.1 23.9 26.7 29.5	.367 .363 .358 .354" .349 .345 24.0 28.3 32.5 '36.8 41.0 45.3
20 per cent, excess ............. , .....					
40.7. ................... ! ........					
60 .....................................					
80 ............... ; ......................					
100 ....................................					
Per cent, of heat lost— No excess air* ........ . ................					
20 per cent, excess ...................					
40 ......................................					
60 ...................................					
80 ......................................					
100 ......................					
					
escape at 200° C., 390° F., a temperature which is attainable, the loss in sensible heat is 7.5 per cent, when no excess air is present, but if 100 per cent, of excess air is used the loss will be 14.4 per cent. When the temperature is 300° C., 570° F., the loss with 100 per cent, excess air is 21.6 per cent, and with 400° C., 750° E., it is 29.5 per cent.
SEC. IXb.—Producers.—In almost all metallurgical operations where gas is used for heating, the fuel in the producer is bituminous